A rotary engine includes a rotary piston carried by a rotary shaft and extending into a combustion chamber. An air/fuel charge is sequentially introduced into each of a plurality of working chambers formed by the rotary piston as it rotates in the combustion chamber. Often, a technique known as charge cooling is employed wherein the air/fuel mixture is routed through engine structures prior to introduction thereof into the combustion chamber to cool the internal engine structures. In addition, the fuel may comprise a gasoline/oil mixture so that lubrication of engine components is accomplished.
Because the rotary piston is eccentrically mounted on the rotary shaft, some type of counterweight structure must also be carried by the rotary shaft on both sides of the piston so that vibration is kept to a minimum. Further, the rotary shaft is typically supported by one or more bearings located on both sides of the rotor structure so that bending moments which could further contribute to vibration are minimized.
A conventional rotary engine of the above type has several disadvantages. Because the rotary assembly includes multiple counterweights and bearings, assembly is complex and size, weight and overall cost are increased. Also, even though charge cooling is typically utilized, a separate cooling system may still be required, thereby resulting in the need for a coolant pump and separate flowpaths in the engine for the air/fuel mixture and the coolant. These structures further undesirably add to the size, weight and cost of the engine. Still further, some rotary engines do not utilize a gasoline/oil mixture but instead are fueled by straight gasoline and have a separate lubrication system for lubricating engine components. In this case engine size, weight, complexity and expense are even further increased.